Cheats have been around as long as gambling. With the advancement of technology, come new methods for cheats to take advantage. One such method involves marking playing cards such that cheats are able to discern a card's identity (i.e., rank and suit) from the card back. Knowing the rank and suit provides the cheat with a tremendous advantage over the casino (e.g., blackjack) or competing players (e.g., poker). Marking playing cards can take many forms including the use of invisible chemicals viewable through special lenses, the use of chemicals only viewable via electronic means, physical demarcations and anomalies, smudges, etc.
It would be useful and advantageous to develop an automatic playing card shuffler and other card-handling devices incorporating means for detecting marked cards of various types to prevent cheats from taking advantage of casinos and competing players.